Method of pulverizing minerals and similar materials



vMETHOD OF PULVERIZING MINERALS AND SIMILAR MATERIALS Filed. Jam. 1B.1932 3 Sheets-Shea?l l Feb, 27, 1934. N. H. ANDREWS Er AL METHOD OFPULVERIZING MINERALS AND SIMILAR MATERIALS Filed Jan. 18, 1932 3Sheets-Sheet 2 Feb. 27;, 3934. N. H. ANREWS ."ET'AL. $948,609

METHOD OP' '.ULVERIZING MINERALS AND SIMILAR MATERIALS Filed Jan., 1a.1932 s sheets-sheet 3 Patented Feb. 27, 1934 UNITED STATES PATENToFF-ICE METHOD F PULVERIZING MINERALS AND SIMILAR MATERIALS ApplicationJanuary 18, 1932. Serial No. 587,268 1s claims. (c1. ss-4s) Heretoforeit has been proposed to pulverize various minerals by the direct head-onimpact of two alined streams of minerals impelled at high velocityagainst each other by steam or other 5 similar fluids under highpressure, but such methods have been destructive to the apparatuses inwhich the processes were performed because of the difficulty inmaintaining the impacting streams in perfect alinement, due to theexpansion and contraction of the parts under the pressures andtemperatures to which the apparatus was subjected.

The lack of alinement of the nozzles during the operation was mostdestructive for that part of the stream of hard'mineral matter which wasunchecked by the opposing stream was driven directly against the wallsof the impact chamber or against the projecting end of the opposingnozzles, with the result that they were quickly worn or abraded anddestroyed. Moreover, the material tubes through which the minerals beingpulverized were impelled were also subjected to great wear and requiredfrequent replacement.

We have discovered that some of the parts heretofore deemed essential toan impact pulverizer, may be dispensed with, and even the metal materialtubes and the metallic impact chamber in which said tubes were mounted.We have also found that an exact alinement of opposing streams is not soessential as heretofore it has been believed, provided the body or massof material under treatment be great enough transversely to prevent thematerial, impelled by the jets, from being driven laterally through themass against the walls.

We have also found that by retaining and enclosing a relatively largequantity or mass of loose material under treatment, on the bottom andsides thereof so as to form a columnar body of lloose material and byburying a plurality of steam jets Well below the upper free surface ofthe wall, with the axes of the steam jets in a relatively horizontalplane and all directed to a focal region preferably'at or about the axisof the column, and by discharging steam at high pressure and velocityfrom said jets, the steam or other suitable fluid under pressure whichmay be used, will form and maintain in the mass of material at saidfocal region a virtual impact chamber; will substantially form tubular.passages through the mass of material from the tips of the jets to saidfocal region which will operate like the metal material tubes heretoforeused, said tubular passages being tapering and through which pieces ofmaterial to be pulverized will be driven in a stream to the point ofimpact of said impact chamber; and will even force through the material,and maintain, a substantially clear passage, extending vertically fromthe focal or impact chamber to the upper free surface of the mass.Through this last-mentioned passage (normally vertical through the massand directly over the impact chamber) all of the material which leavesthe impact chamber or cavity comprising dust and tailings is impelled ata high rate of speed upwardly as a 'uni-directional stream and isdischarged into an initial separator directly over the mass in thematerial chamber Where a separation of the dust from the heavierparticles or fines maytbe effected, the heavier fines fallinggravitationally back onto the top of the mass of material being treated,for retreatment or further pulverization andthe dust being carried awayfloating in the stream of steam passing through and out of theseparating chamber.

We have further discovered that a practical and substantialpulverization of a restrained mass of loose material can also beeffected in a similar way, by the action of one or more pairs or sets ofsubstantially opposed jets, the axes of which pairs being parallel, andfurther that a substantial pulverization of such a confined mass ofloose material can be effected by one jet or a plurality of jetsdisposed parallel to each other and without the use of opposing jets,and without an independent delivery tube, provided the mass, in thedirection of the discharge from the jets, is deep or thick enough toprevent the pieces, impelled at high velocity, from being driven throughthe mass against the restraining Wall and provided the distance betweenthe surface level of the mass and the axes of the jets is not so greatthat the steam cannot force its way up through the mass and form andmaintain a virtual delivery tube, the walls of which are composed of thematerial itself.

The ob-ject of the present invention is to Vsimplify the process ofpulverizing minerals and similar materials by impact, by forming andmaintaining within a confined body of loose material, under treatment, avirtual impact chamber at a focal point or region within the mass, bydischarging into the mass a plurality of opposed jets of dry steam underhigh pressure and having a high velocity, all the jets being directed tosaid focal point or region Within the mass, from which chamber all thematerial is expelled by the steam after impact in a unidirectionalstream, upwardly directed, and of high velocity, and by effecting aseparation of the heavier particles from the sumciently pulverizedparticles in an expansion chamber immediately above the level of thefree upper surface of the material under treatment and of which saidfree upper surface forms the bottom of the expansion or primaryseparation chamber, whereto the heavier particles gravitationally fallin said separation chamber to the mass of material under treatment andare re-subjected to the pulverizing action of the jets, the suilicientlypulverized particles being floatingly carried out of said chamber by thecurrent of steam filling said chamber.

A further object of this invention is to utilize the material undertreatment in such a way that the said material forms the wall of theimpact chamber in order that the impact of the pieces impelled at highvelocity against the walls of said chamber after the impact of thestreams will produce a further reduction of the material to powder.

A further object of this invention is to provide a process whereinminerals and similar substances may be pulverized by impact byprojecting steam at high temperature and velocity into a loose mass ofmaterial to be pulverized but restrained at the sides and bottom thereofeven when the jets are not opposed and are not circularly arranged ordirected to a common focus, provided the restrained mass is thickenough, in a direction in which the jets project, to deflect the streamupwardly through the mass to the upper unrestrained surface of the massunder treatment forming within the mass virtual delivery tubes, thewalls of which are composed in the material under treatment.

A further object of this invention is to make, when so desired, such asiron dust, foreign to the material being treated, the impact beingwholly between the pieces of the material under treatment. When metalmaterial tubes and metal impact chambers are used as in the impactpulverizers heretofore constructed, those parts are subjected to so muchabrasion that an impact pulverizer is unsuited to the pulverization ofsome minerals, such as certain pigments wherein even a trace of ironwould affect and change the tint of the product.

A further object is therefore to provide a process which can bepracticed without the use of metal or other material foreign to themineral under treatment, at points where such metal would be subjectedto substantial abrasion.

Further objects of this invention will appear in. the specification andclaims below.

In the drawings forming a part of this specification and in which thesame reference figures are employed throughout the various views todesignate the same parts,

Fig. 1 is a vertical central section of one form of apparatus which isadapted for the performance of the process, comprising the presentinventon;

Fig. 2 is a horizontal transverse section of the same on the line 2--2of Fig. 1;

Fig. 3 is an apparatus similar to that shown in Fig. 1 but in which themetal delivery tube, shown in Fig. 1, is omitted;

In Figs. 4 to 9 are diagrammatically illustrated several modifiedprocesses embodying the invention. In Fig. 4 is shown a modifiedapparatus, similar to that shown in Fig. 1 but employing two parallelpairs of opposed jets;

Fig. 5 indicates an apparatus Similar 110 that shown in Fig. 4 butwherein the metal delivery tube is omitted;

Fig. 6 is a horizontal sectional view on the line 6--6 of Figs. 4 and 5:

Fig. 'l indicates a modification wherein the jets are not opposedstreams;

Fig. 8 shows a modification wherein the metal delivery tube is omitted;

Fig. 9 is a horizontal sectional view on the lines 9-9 of Figs. 'I and8; and

Fig. 10 is a fragmentary diagrammatic view in horizontal cross-sectionindicating the general shape of the virtual impact chamber when op-`posed jets are a little out of alinement.

Referring rst to the form of apparatus illustrated in Figs. l and 2, thepulverizer comprises a circular steam header 1 which is provided with acontinuous circular passage 2. Superheated steam at high pressure isdelivered by a pipe 3, controlled by a valve 4, to the annular passage 2of the circular steam header 1. Also communieating with the chamber orpassage 2 is a circular series of steam jets or nozzles 5 all directedinwardly substantially to a focus 6 at the center of the circular seriesof jets, the jets being preferably spaced equidistant from each otherand arranged with their axes substantially in a common horizontal plane.

The apparatus is preferably provided with a bottom plate or closure 7which in turn is preferably provided with a hole 8 closed or covered bya pan 9 bolted thereto and which, during the operation of the apparatusremains full of the loose material under treatment as will be referredto again below.

Extending upwardly from the circular header l is a cylindrical housing10, the upper end of which is substantially closed by a cover or closure11 preferably tapering upwardly inwardly to a cylindrical throat 12which in turn communicates with the lower end of a separator 13. Thethroat 12 is provided with a valve or damper 14 by which the flow ofsteam and dust from the housing 10 into the separator 13 may beregulated and controlled.

Mounted within the housing 10 and preferably concentric with respectthereto is a delivery tube l5, the lower end of which is located alittleabove the focus 6 of the axes of the jets and the upper end of whichextends well up into the upper portion of the housing 10. This deliverytube l5 may be rigidly supported in any suitable manner, as by brackets16 having their outer ends secured to the inner surface of the housing10 and their inner ends rigidly secured to the outside of the deliverytube 15. The upper end of the tube 15 is alsopreferably provided with abaille or impact plate 17, of hard metal or of iiint, held separatedwell above the upper end of the delivery tube 15 by supporting rods orbrackets 18.

The apparatus also is preferably provided with a chute or feed tube 19extending through the wall of the housing 10 and through which thematerial 20 to be pulverized is continuously delivered. The uppersurface 21 of the material 20 14C in the housing 10 is maintained at asubstantially constant level between the inner wall of the housing 10and the outer wall of the deliv ery tube 15.

To insure a constant downward travel of the 14.3 material 20 within thehousing 10 and to keep the top surface 21 of the material approximatelylevel, we preferably provide a circular distributing member 22 supportednear its periphery by a ring-like seat 23 secured to the inner surfacei5( of the housing 10, said 'member 22 being provided with teeth 24adapted to mesh with the teeth of a driving pinion 25 mounted on ashatt26 journaled outside of the housing 10, the pinion 25 passing through aslot in the housing 10 to engage the teeth 24 of the distributing member22. This distributing member is provided with a circular series ofopenings 28 therethrough, one edge of each opening being provided with avane 29 projecting downwardly.

The distributing member 22 also has a circular opening 30 slightlyspaced from the outer surface of the delivery tube 15 and through thesaid delivery tube 15 extends vertically. So mounted the member 22 isslowly rotated.

Above the distributing member 22 is an inwardly and downwardly flaringor tapering flange 27 secured to the interior of the housing at itsupper end and having its lower end overlying the upper surface oftheperiphery of the distributing member 22 for the purpose of preventingthe material 20 from flowing into the teeth 24 of the distributingmember 20 and for thus keeping the engagement of the said teeth with thepinion 25 clear of said material 20.

In the practice of the process of this invention, sand, coal or othermineral matter to be pulverized, is admitted into the housing 10 throughthe chute 19 and the distributing member 22 is slowly rotated by thepinion 25 until the housing 10 is filled substantially to the level ofthe upper edge of the opening through the chute 19. The lower portion ofthe housing 10 then forms a material chamber 10a and the upper part ofthe housing 10 above the level of the upper surface 21 of the material20 constitutes an uptake or primary separating or expansion chamber 10b,the upper end of the delivery tube 15 extending well into the uptakechamber 10b and above the upper surface 21 of the material 20 whichforms the floor of vthe said primary expansion chamber 10b.

Superheated steam at high pressure and temperaure is supplied to thejets or nozzles 5 by opening the valve 4. The openings at the dischargeends of the jets or nozzles 5 are small and the dry steam at highpressure issues therefrom into the body of material 20 at a very highvelocity with the result that it drives into the mass and almostimmediately forms and maintains in the said mass of material 20 avirtual impact chamber 31 in the focal region at and around the truefocus 6 of the jets; forms and maintains substantially clear taperingpassages 32 extending from the tips of the nozzles 5 respectively to thevirtual impact chamber 31; and drives the material immediately afterimpact upwardly at a high rate of speed as a stream of steam and rapidlymoving pieces of solid matter through the delivery tube 15 and againstthe baffle or impact plate 17 which is preferably made of flint or hardsteel. After its impact against the baille or plate 17 the stream ofmaterial and steam discharges substantially horizontally between thebrackets or supports 18 into the up- 4take chamber 10b wherein thevelocity of the steam issuing from the delivery tube or pipe 1'5 isgreatly reduced by reason of the expansion of the steam from the pipe 15into the relatively large chamber 10b. j

This uptake chamber l()b therefore forms a primary separator by means ofwhich the particles of material which have been suiliciently finelycomminuted by reason of their impact in the impact chamberand againsteach other in 'i their travel through the delivery tube 15 and by befloated away on the upwardly moving current of steam in the chamber 10bfall by gravity and come to rest upon the upper surface 21 of thematerial 20 filling the lower part of the housing 10 or the materialchamber 10B.

We have found that the material which is impelled by the jets issuingfrom the nozzles 5 is mainly supplied to the virtual material tubes 32from points at or about the tips of the nozzles 5 and that it is thatmaterial which is impelled by the high velocity jets of steam throughthe virtual material tubes or tapering passages 32 into violent impactwith like streams impelled by the other jets to the same focal point 10C6. The quantity of steam so delivered by the jets 5 and the pressure atwhich it is supplied immediately forms in the body of the material 20the virtual impact chamber 31 whence, after impact, the impingingmaterial has but one direction to follow, to wit, upwardly through thedelivery tube 15. It is true that below the plane of the axes of thejets the impinging material tends to drive downwardly against the massof material and where it forms a chamber extending a little below theplane of the axes of the jets 5, but a balanced condition is almostimmediately attained, a constant layer of unpulverized material ismaintained over the pan 9 and substantially all the material afterimpact is swept or impelled or driven in a single direction, and thatupwardly, through the delivery pipe 15 whence it strikes after impactagainst the plate or baille 17 and then passes substantiallyhorizontallyv into the uptake chamber l0b where the initial separationof the tailings from the dust is effected. Thetailings and heavierparticles fall gravitationally back to the surface 21 of the mass ofmaterial being treated in the pulverizer and thus travel slowlydownwardly under the ac 1-5 tion of gravity and the distributing member20 to points adjacent the nozzles 5 by which in time they are againcaught or are picked up by the stream of steam issuing from the nozzlesand are further pulverized by their impact with opposing streams. As thelevel 21 of the mass of material in the material chamber lowersslightly, as the material is pulverized by the jets and floats out ofthe uptake chamber 10b, the upper edge of the opening of the chute 19becomes uncovered slightly, whereupon more of fresh materialgravitationally flows into the material chamber 10. Thus the level ofthe upper surface 21 of the material in the material chamber 10Il ismaintained substantially constant and thel distance from the plane ofAthe axes of the jets to th e free upper surface of the mass issubstantialy ly unchanged during the operation.

Of course, seldom do two pieces of material driven by opposed streams ofsteam at high pressure strike absolutely head-on squarely against eachother, but after impact they may strike against the side and bottomwalls of the impact chamber and may momentarily have an orbital movementaround the focus 6, but the steam in the impact chamber can only emergefrom the impact chamber by moving upwardly out through the delivery tube15 since the mass of loose material is confined at its bottom and sides.The walls of the virtual material tubes 32 and the walls of the virtualimpact chamber 31 are thus composed of the very material which is beingpulverized and any impact of the flying material against the walls ofthe tubes or passages 32 or against the walls of the impact chamber 31or against each other in their travel or in their impact with opposingstreams all contributes to the rapid comminution and reduction of theparticles to a powdered condition. The reduction of the material to apowdered condition is relatively rapid and that which has been reducedto a sufficiently fine powder is borne away as fast as it is formed upout of the uptake chamber 10b and into the separator 13 where a furtherfiner separation of the coarser from the iiner particles may be effectedwhen it is desirable to produce a very finely powdered product.

When the apparatus is used for pulverizng anthracite coal, for whichthis process is particularly adapted, the separator 13 may be dispensedwith and the stream of dust and steam passing through the throat 12 maybe conducted through a suitable tube and conveyed directly to theiirebox of a boiler or other apparatus in which the powdered coal' is tobe burned, thus eliminating entirely the necessity of first .collectingthe powdered coal, then transporting it to a storage bin and thenconveying it by a suit' able feeding apparatus to the fire box. Thisintermediate collecting, handling and storing of the powdered productmay thus be entirely dispensed with in the practice of this invention byfeeding the pulverized coal directly from the pulverizer to the boilerin which it is to be consumed.

In the modification shown in Fig. 3, the metal delivery tube 15 isomitted and the baille or deiiector 1'? in the uptake chamber is conicaland depends from the top or closure 11 thereof, being rigidly supportedby rods or brackets 18. 1n other respects the construction issubstantially identical with that shown in Figs. 1 and 2.

In this apparatus the steam at high pressure is projected into the massof material 20 from the jets 5 toward a common center or focal regionand they form and maintain the tubular tapering passages 32 and thevirtual impact chamber 31 as they do in the apparatus shown in Fig. 1.But the steam at or about the focal point 6 in the mass is under highpressure and is moving at high velocity. Since the mass of loosematerial is restrained and confined at the bottom and sides and cannotyield in those directions, but is unrestrained on its upper side, thesteam discharges from the impact chamber 31 upwardly through theunrestrained upper surface 21 and forms and maintains a tubular passage15a straight through the mass, thus forming a virtual delivery tube 15a,functioning like the tube 15, shown in the construction of Fig. 1, inthat, through it, all of the material, both fine and coarse, afterimpact, is violently impelled at high velocity against the baule ordeflector 1'7xi in the primary separating chamber l0b over the materialin the material chamber 10a whence it is deflected horizontallyradially, and a primary separation of the dust from the insufficientlypulverized particles is effected, the heavy particles fallinggravitationally to the top 2l of the mass in the material chamber 10bfor retreatment, while the light, sufficiently pulverized particles arecarried by the current of steam upwardly between the bars 18 and outthrough the throat 12.

We have found that it is not absolutely necessary to have the jets 5 inexact alinement or to direct them to an exact focal point, provided thecolumnar body of loose material in the material chamber is thick enoughhorizontally to prevent the steam from driving straight through it tothe opposite side wall of the cylindrical housing 10 or to the oppositeside of the header 1. (See Fig. 10).

If the streams are directed a little to one side of the focus no harmwould ensue for the thickness of the mass of the material between thevirtual impact chamber 31c and the housing l0 is sufficient to stop therapidly driven pieces of material before they reach the wall. This istrue even when only two substantially alined and opposed jets are usedinstead of more than two as shown in the drawings. Where three or morejets are employed any similar lack of alinement of a jet with the focus6 does not detract from the efficiency of the device. The shape of thevirtual chamber 31c may become somewhat elongated and the rapidly movingpieces of material in the impact chamber may be subject to a circular ororbital movement around the focal point, but such motions and the impactof the pieces against each other and against the wall and bottom of theimpact chamber 3lc and against the walls of the virtual uptake deliverytube 15 could only tend to supplement and accelerate the comminution ofthe pieces and to increase the eilciency of the apparatus by effecting amore rapid pulverization of the mass as a whole.

But Where the mass of material in the material chamber is backed andretained by a rigid wall or by a rigid bottom plate the velocity of thestreams of material, particularly after impact, is not generallysufficient to drive the pieces deeply into the mass, particularly if theoutlet from the impact chamber is provided by the tube 15, or after thevirtual delivery tube 15 has been formed, vertically therefrom. It isfor this reason that the relatively thin layer of sand or loose materialbetween the bottom of the virtual irnpact 31 and the closure or pan 9 isample to prevent the flying pieces from driving through it to the metalclosure.

Having thus described with considerable particularity two types ofapparatuses in which the present invention may be practiced, a briefdescription of further modifications of the process with diagrammaticreference to the apparatus will now suffice.

In Figs. 4 and 5 are illustrated diagrammatically two modifiedarrangements wherein a pair of jets 5 5 are alined as distinguished frombeing directed to a common focal point, and wherein are employed fourjets arranged as two pairs of opposed alined jets 5-5-5-5 all directedsubstantially to a control or focal region, all within a housing 10'which may be of rectangular or of any other suitable shape instead ofcircular in horizontal cross-section.

Referring to the modification shown in Figs. 4 and 6 steam issuing fromeach pair of alined jets 5--5 forms, in the mass 20, the same virtualmaterial tubes 32 that they do in the apparatus shown in Figs. 1 and 3,but when the pairs of alined jets are relatively close to each other asis indicated in Fig. 6 they form a virtual impact l chamber 31 which iselongated and in which the material issuing from one pair of opposedjets 5 5, and after impact, some of the material is thrown toward theaxis of the cooperating pair of alined jets 5 impacting against thematerial similarly projected by that other pair of alined jets 5-5 thuseffecting a further pulverization of the product by impact, as isclearly shown by the arrows in the impact chamber 31 shown in Fig. 6.

In this apparatus is shown a delivery tube 15b which may be supported asshown in Fig. 1, but

which will be elongated transversely to conform to and overlie theelongated impact chamber 31a. 15a is preferably providedv a suitabledeflector 171 in the primary separation chamber 10b to deflect thematerial laterally after its impact with the deector 17h, and theheavier particles fall in the separation chamber 10b to the surface 21of the mass 20 in the material chamber 10a.

In thismodiiication the lighter particles are carried by the steam llingthe separation chamber 10b upwardly out through the throat 12.

In Fig. 5 the arrangement is exactly like that shown in Fig. 4 exceptthat the tube 15b is omitted. It therefore bears the same relation tothe apparatus shown in Fig. 4 that the arrangement shown in Fig. 3 bearsto that in Fig. 1. In this case the steam leaving the impact chamber 31aforms a virtual delivery tube 15c extending vertically upwardly throughthe mass 20 from the impact chamber 31 through this passage 15c all thematerial after impact is ejected as a stream at high velocity againstthe deflector 17h, as it does in the apparatus shown in Fig. 3.

The horizontal section through the axes of the jets 5-5-5--5, on theline 9-9 through the two apparatuses shown in Figs. 4 and 5 areidentical and are shown in Fig. 9.

In Figs. 7 to 9 inclusive are shown two further modications of ourimproved process to demonstrate the fact that when the width orthickness of the constrainedmass of loose material 2O is sufficient, topreclude pieces impelled by the jets 5 from completely penetrating themass to the opposite wall of the housing 10, it may not be necessary touse opposing streams of material impelled by opposing jets.

Thus in Fig. l the casing or housing 10" may be rectangular and the jets5--5--5-5 may be arranged to discharge steam in the mass 20 parallel toeach other and in the same horizontal direction. In this case each jetwill form through the mass a virtual material tube 32 as in thepreviously described modifications, but as the stream approaches theopposite wall of the casing 10 it will be opposed by the material 20adjacent that wall, and the impact chamber 31b4 will be formed where thestream of material propelled through the material tube 32 is checkedagainst the material adjacent the opposed wall. If, therefore, adelivery tube 15b like that shown in Fig. 4 be supported directly overthe impact chamber 31b as shown in Fig. 7 all the material after impactwill be forced by the steam delivered from the jets 5 upwardly throughthe delivery tube 15b against the deflector 17 and thence horizontallyinto the separator chamber 10b in which the heavy particles will fall tothe bottom of the chamber and consequently to the surface 21 of the mass20 for retreatment, and the lighter particles will be floated out of thechamber 10b through the throat 12 either to such Above the upper end ofthe delivery tube a. separator as ls indicated in Fig. 1 or to any othersuitable place.

In Fig. 8 the apparatus is exactly like that shown in Fig. 7 except thatthe upwardly directed delivery tube 15b is omitted and the steam fromthe impact chamber 31b forms and maintains a virtual delivery tubelthrough the material itself and through the delivery tube all thematerial after impact is impelled upwardly against the deflector 17c asin Fig. '7.

In all the various modifications of this invention the steam from thejets 5 is discharged at high pressure and at high velocity directly intothe mass of loose material to be pulverized, the loose material beingrestrained from movement in all directions but one, that one preferablybeing the vertical direction through the top surface of the mass; thevelocity of the steam projected into'the mass is so great that it formsand maintains virtual material tubes through which material of the massis impelled at highA speed into a virtual impact chamber; the steamissuing from the jets at high velocity and pressure forms within themass a virtual impact chamber in which the impact is between streams ofmaterial issuing from opposed jets or with the Wall of the impactchamber itself; after leaving the impact chamber the steam deliveredthereto drives substantially all the material (both ne and coarse) outof the impact chamber upwardly, through either an actual delivery tubeextending Yfrom the impact chamber to a point well above the level ofthe free surface of the mass, or through a virtual delivery tube formedby the steam itself driving through the mass upwardly from the impactchamber; the upper surface of the mass of loose material under treatmentforms the lower wall of a primary separation chamber into which thesteam from the delivery tube expands and in which the speed of the steamis reduced sufliciently to permit the heavier particles to fall bygravity to the upper surface of the mass for retreatment; and the lightsufficiently ground particles or dust are floatingly borne by the steamfilling the separator chamber out of the separator forV a furtherseparation or for collection or to any desired place or position for useor storage.

It is not to be understood that applicants regard the modifications ofthe process, particularly as illustrated in Figs. 'I and 8, to be asemcient, generally speaking, as when carried out by such constructionsas are indicated in Figs. 1 to 3, which permit of the use of a largenumber of jets directed to a common focal point wherein a violent impactis attained and a rapid reduction of hard materials to a very finepowdery condition is easily effected. But the process may be carried outwith a plurality of jets arranged in parallelism, in the'mannerindicated in Fig. 9 when relatively soft material is to be pulverizedand the degree or neness to which the material is to be reduced is notan essential consideration:

From the foregoing disclosures, it is apparent that many changes may bemade and that many details may be varied in applying the principle ofour invention to the pulverization by impact of various materials ofvarying degrees of hardness and in the production of powders ofdiffering degrees of neness, and it is not our intention to limit ourinvention to the exact steps or to the precise procedures hereindisclosed so long as such changes and variations fairly fall within thespirit and scope of the appended claims.

Having thus described our invention, what we claim and desire to protectby Letters Patent of the United States is:

1. The method of pulverizing minerals and the like, which consists inconfining the mass of loose mineral matter to be pulverized by enclosingthe said mass on the bottom and sides thereof and discharging into themass a plurality of substantially opposed streams of a gaseous fluid athigh velocity, the axes of said streams being located at a substantialdistance below the freeupper surface of said mass and substantiallymeeting at a focal point or region within said mass, the pressure andvelocity of the said iiuid being suficient to form and maintain withinthe mass at the said focal region a virtual impact chamber, the sidewalls and bottom of which are composed of the loose material of the massand to form and maintain substantially tubular passages through the massfrom the point where the said uid is discharged into the mass to thesaid impact chamber through which tubular passages some of the loosematerial of the mass is impelled by said streams of said fluid at highspeed into impact in said impact chamber with similar opposed streams.

2. The method. of pulverizing minerals and the like, which consists inconfining the mass of loose mineral matter to be pulverized by enclosingthe said mass on the bottom and sides thereof and discharging into themass a plurality of substantially opposed streams of a gaseous uid underpressure at high velocity, the axes of said streams being located at asubstantial distance below the free upper surface of said mass andsubstantially meeting at a focal point or region within said mass, thepressure and velocity of the said fluid being sufficient to form andmaintain in the mass at the said focal region a virtual impact chamber,the said walls and bottom of which are composed of the loose material ofthe mass and to form and maintain substantially tubular passages throughthe mass from the point where the said iiuid is discharged into the massto the said impact chamber through which tubular passages some of theloose material of the mass is impelled by said streams of said fluid athigh speed into impact in said impact chamber with similar opposedstreams, the pressure and Velocity of the said fluid after the impact ofopposed streams in said impact chamber being operative to impel all ofthe material leaving the impact chamber after impact in one direction athigh velocity, said direction being upwardly at right angles to theplane of the axes of said streams.

3. The method of pulverizing minerals and the like, which consists inconfining the mass of loose mineral matter to be pulverized by enclosingthe said mass on the bottom and sides thereof and discharging into themass a plurality of substantially opposed streams of a gaseous fluidunder pressure at high velocity, the axes of said streams being locatedat a substantial distance below the free upper surface of said mass andsubstantially meeting at a focal point or region within said mass, thepressure and Velocity of the said uid being sufficient to form andmaintain in the mass at the said focal region a virtual impact chamber,the said walls and bottom of which are composed of the loose material ofthe mass and to form and maintain substantially tubular passages,

through the mass from the point where the said uid is discharged intothe mass to the said impact chamber through which tubular passages someof the loose material of the mass is impelled by said streams of saiduid at high speed into impact in said impact chamber with similaropposed streams, the pressure and velocity of the said iiuid after theimpact of opposed streams in said impact chamber being operative toimpel all of the material leaving the impact chamber after impact in onedirection at high velocity, said direction being upwardly at rightangles to the plane of the axes of said streams, into an expansion andseparator chamber immediately above said mass of material undertreatment into which the heavier particles fall gravitationally to theupper free surface of said mass and from which the finely pulverizeddust is carried away by said fluid.

4. The method of pulverizing minerals and the like, which consists inconfining the mass of loose mineral matter to be pulverized by enclosingthe said mass on the bottom and sides thereof and discharging into themass a plurality of substantially opposed streams of a gaseous fluidunder pressure at high velocity, the axes of said streams being locatedat a substantial distance below the free upper surface of said mass andsubstantially meeting at a focal point or region within said mass, thepressure and velocity of the said uid being suflicient to form andmaintain in the mass at the said focal region a virtual impact chamber,the said walls and bottom of which are composed of the loose material ofthe mass and to form and maintain substantially tubular passages throughthe mass from the point where the said fluid is discharged into the massto the said impact chamber through which tubular passages some of theloose material of the mass is impelled by said streams of said fluid athigh speed into impact in said impact chamber with similar opposedstreams, the pressure and velocity of the said uid after the impact ofopposed streams in said impact chamber being operative to impel all ofthe material leaving the impact chamber after impact in one direction athigh velocity, said directionI being upwardly at right angles to theplane of the axes of said streams, then reducing the speed of the streamof said fluid leaving said impact chamber by expanding it into aseparating chamber, the bottom of which is formed by the top surface ofthe mass of material under treatment whereby the insufficientlypulverized heavier particles fall gravitationally to the top of saidmass under treatment and the sufficiently small dust-like particles areborne away by said iiuid as it passes through said separator chamber.

5. The method of pulverizing minerals and the like, which consists inconfining the mass of loose mineral matter to be pulverized by enclosingthe said mass on the bottom and sides thereof and discharging into themass a plurality of substantiallyvopposed streams of a gaseous iiuidunder pressure at high velocity, the axes of said streams being locatedat a substantial distance below the free upper surface of said mass andsubstantially meeting at a focal point or region within said mass, thepressure and velocity of the said fluid being suflicient to form andmaintain in the mass at the said focal region a virtual impact chamber,

the said walls and bottom of which are composed of the loose material ofthe mass and to form and 'maintain substantially tubular passagesthrough the mass between the point where the said fluid is dischargedinto the mass to the said impact chamber through which tubular passagessome of the loose material of the mass is impelled by said streams ofsaid fluid at high speed into impact in said impact chamber with similaropposed streams, the pressure and velocity of the said iiuid after theimpact of opposed streams in said impact chamber being also operative toform and maintain a substantially clear passage through the mass fromthe said impact chamber to the upper free surface thereof through whichall the material after impact is impelled in a stream of said fluid ofhigh velocity in one direction, said dlrection being vertically upwardlyfrom said impact chamber.

6. The method of pulverizing minerals and the like, which consists inconflning the mass of loose mineral matter to be pulverized by enclosingthe said mass on the bottom and sides thereof and discharging into themass a plurality of substantially opposed streams of a gaseous fluidunder pressure at high velocity, the axes of said streams being locatedat a substantial distance below the free upper surface of said mass andsubstantially meeting at a focal point or region within said mass, thepressure and velocity of the said fluid being sufficient to form andmaintain in the mass at the said focal region a virtual impact chamber,the said walls and bottom of which are composed of the loose material ofthe mass and to form and maintain substantially tubular passages throughthe mass from the point where the said fluid is discharged into the massto the said impact chamber through which tubular passages some of theloose material of the mass is impelled by said streams of said iiuid athigh speed into impact in saidimpact chamber with similar opposedstreams, the pressure and velocity of the said iiuid after the impact ofopposed streams in said impact chamber being operative to impel all ofthe material leaving the impact chamber after impact in one direction athigh velocity, said direction being upwardly at right angles to theplane of the axes of said streams, the depth of the material above theplane of the axes of said streams being maintained substantiallyconstant by the slow addition thereto of fresh material to bepulverized.

7. The method of pulverizing mineralsand the like, which consists inconfining a mass of loose mineral matter to be pulverized by enclosingthe mass on the bottom and sides thereof and discharging, through asmall orifice, into the mass, a stream of a suitable iiuid underpressure land at high velocity, the axis of said stream beingsubstantially horizontal and located at a substantial distance below theupper free surface of said mass, the pressure and velocity of the saidiiuid being sufficient to form and maintain substantial tubular passagesin the mass through which some of the loose material of the mass isimpelled at high speed by said stream of said fluid into impact withother pieces of the material of the mass in said impact chamber, toreduce said pieces to powder by impact.

8. The method of pulverizing minerals and the like, which consists inconfining a mass of loose mineral matter to be pulverized by enclosingthe mass on the bottom and sides thereof 'and dischargingthrough arelatively small orifice into the mass, a stream of a suitable fluidunder pressure, the axis of said stream being substantially horizontaland at a substantial distance below the upper surface of said mass, thepressure and velocity of the said iiuid being sufficiently high to formand maintain within said mass a virtual impact chamber, the walls andbottom of which are composed of the loose material of the mass, to forma straight tubular passage through the mass from said orifice to saidimpact chamber and to form a passage from said impact chamber to thesurface of said mass through which the pieces of the mass are impelledvertically upwardly by said iiuid after impact in said impact chamber.

9. The method of pulverizing minerals and the like, which consists inconfining the loose mineral to be, pulverized by enclosing the mass onthe bottom and sides thereof and discharging through a relatively smallorifice, into the mass, a stream of a suitable iiuid under pressure, theaxis of said stream being located at a substantial distance below theupper free surface of said mass, the velocity of the said iiuid beinghigh and suficient to form and maintain in the mass a virtual impactchamber, the walls and bottom of which are composed of the loosematerial of the mass; to form and maintain substantial virtual passagesthrough the mass from the point where the said iiuid is discharged intothe mass; to the said virtual impact chamber through which tubularpassage some of the loose material of the mass is impelled by saidstream of said fluid at high speed into said impact chamber; and to alsoform and maintain a vertical passage from said impact chamber throughand to the upper surface of said mass through which vertical passageafter impact are impelled at a high rate of speed by and in said iiuidsubstantially all the contents of said impact chamber after impacttherein.

10. The method of pulverizing minerals and the like, which consists inconfining the loose mineral to be pulverized by enclosing the mass onthe bottom and sides thereof and discharging, from an orifice, into themass, a stream of a suitable iiuid under. pressure, the axis of saidstream being substantially horizontal and at a substantial distancebelow the upper free surface of said mass, the velocity of the saidiiuid being ample to form and maintain in the loose mass a virtualimpact chamber, the Walls and bottom of which are composed of the loosematerial of the mass and to also form and maintain substantial virtualpassages through the mass from the point where the said iiuid isdischarged into the mass to the said virtual impact chamber throughwhich tubular passage some of the loose material of the mass is impelledby said stream of said iiuid at high speed into said impact chamber, thepressure and velocity of the said fluid after impact in said impactchamber, being operative to impel all of the material out of saidchamber as a stream moving at high velocity upwardly through the mass,and effecting a separation of the tailings from the dust immediatelyover said mass being treated whereby the tailings by gravity arereturned directly to said mass for retreatment.

11. The method of pulverizing minerals andV the like, which consists inconfining the loose mineral to be pulverized by enclosing the mass onthe bottom and sides thereof and discharging through a relatively smallorifice, into the mass, a stream if a suitable fluid` under pressure,the axis of said stream being located at a substantial distance belowthe upper free surface of said mass and substantially parallel thereto,the pressure and velocity of the said fluid being ample to form andmaintain in the loose mass a virtual impact chamber, the walls andbottom of which are composed of the loose material of the mass and toalso form and maintain substantial virtual passages through the massfrom the point where the said fluid is discharged into the mass to thesaid virtual impact chamber through which tubular passage some of theloose material of the mass is impelled by said stream of said fluid athigh speed into said impact chamber, the pressure and 'velocity of thesaid fluid after impact in said impact chamber, being operative to impelall of the material out of said chamber as a stream moving at highvelocity upwardly through the mass, and effecting a separation of thetailings from the dust above the level of the mass of material undertreatment and gravitationally returning said tailings to said mass forfurther pulverization by impact.

12. The method of pulverizing mineralsan the like, which consists inconning a mass of loose pieces of mineral matter to be pulverized on thebottom and sides thereof and discharging into the mass, a plurality ofsubstantially opposed streams of a suitable fluid at high velocity, theaxes of said streams being substantially horizontal and located at asubstantial distance below the free upper surface of the mass undertreatment, the pressure and velocity of the fluid being sufcient to formand maintain within the mass at the focal region a virtual impactchamber the side walls and bottom of which are composed of the loosepieces of the material of the mass, and to form and maintainsubstantially tubular passages through the mass between the point wherethe uid is discharged into the mass to the said impact chamber andthrough which tubular passage some of the loose material of the mass isimpelled by the said streams of uid at high speed into impact in saidimpact chamber with similar opposed streams.

13. The method of treating minerals and similar hard substances whichconsists in impelling, in a body of loose material under treatmentopposed streams of said material against each other at high velocity,said streams being impelled each by a jet of dry gaseous fluid underhigh pressure, the axes of said streams being substantially directedagainst each other to a focal region in an impact chamber in saidmaterial, said axes lying in a substantially horizontal plane, allmaterials after impact being directed outwardly from said impact chamberin a single stream normally moving at a high velocity in a directionupwardly at right angles to said common plane, impelled by the expandinguid from said jets after impact, and to a position over the mass ofloose material being treated and then reducing the velocity of saidstream issuing from said impact chamber and separating the tailingstherefrom at a point above the level of the material being treated bysaid jets and gravitationally returning substantially all said tailingsdirectly to said mass of material for retreatment by said jets.

NORWOOD H. ANDREWS. WALTER J. WILLOUGHBY.

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